Bulk materials, such as powders, leaf and root crop products, metal castings, plastic resins, and many other materials are typically placed in large-volume containers for handling and storage of the bulk materials. Generally, the containers provide sturdy walls and closeable openings for protecting the bulk materials while allowing the containers to be handled by equipment such as fork lift trucks and platen trucks.
Some containers also facilitate the drying and curing of the bulk materials. For example, some leaf products are held in containers made with wood-slats that are secured together with enwrapping metal bands. There are gaps between adjacent edges of the wood slats in the wall of the container. As the leaf products emit moisture and dry, the moisture is communicated from the container through the gaps to the atmosphere. The escape of the moisture prevents mold from attacking the leaf products. These containers also allow for long-term storage of the leaf products. This enables the products to cure to useful raw material. The containers have sturdy walls which enable the containers to be stacked for storage in warehouses.
Since the total weight of a single loaded container may run as high as fifteen hundred (1500) pounds, the packing and shipping of bulk materials presents several unique problems. One problem is that such bulk materials are typically poured or thrown into the container and shipped loose so that the packed materials "flow" about the interior of the container. Materials of lesser densities may be pressed or compacted during filling of the container. After filling, the memory of the packed material exerts an outward force on the side walls of the pack. The side walls of the container must be sufficiently rigid in the horizontal plane to withstand internal movement or expansion of the materials and thereby must resist against bulging as a result of internal material flow. Another problem is that the side walls of the container must also be sufficiently rigid to permit stacking of one container on top of another. The side walls must provide sufficient compression strength to prevent any deformation or collapse of the container when others are stacked upon it.
U.S. Pat. No. 4,635,815 discloses a corrugated paperboard container having an exterior tubular corrugated paperboard body laminated to an interior tubular corrugated paperboard body, and includes a plurality of support members fixedly secured between the exterior and interior bodies so as to reinforce the container. While this container has been successful in long-term storage of bulk materials, it has not been gainfully used with fresh leaf products. The corrugated paperboard would prevent escape of moisture from the container. The leaf products would become damaged by mold and decay which leads to lost value. The leaf products must first dry by removal of the moisture held in the leaf products before long term storage can be made successfully with paperboard-type containers. However, transfer of such leaf products from the wood slat containers to the corrugated paperboard container after drying is not efficient. The wood slat containers have drawbacks to their continued use for leaf products. These problems include the costs and availability of such containers.
Accordingly, there is a need in the art for an improved air-breathable container that facilitates communication from the container of moisture emitted from the leaf products held in the container for drying and long-term storage. It is to such that the present invention is directed.